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Volcanic Drill


Fraser Gale

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Fraser Gale

I read somewhere yesterday that a certain volcano that caused aviation a lot of trouble several years ago, is threatening to do the same again.  So just for fun I thought I'd provide a crew refresher on the volcanic ash encounter drill:

IF SUPERSONIC: throttles 18 degrees

IF SUBSONIC: throttles to idle

Descend using 380kts speed and/or turn to exit ash cloud as quickly as possible

MSA: check

IF ALL FOUR ENGINES FLAME OUT:  apply four engine flameout above M1.2 or below M1.2 procedure as appropriate

WHEN CLEAR OF ASH CLOUD or APPROACHING MSA: throttles as required.

END//

This was a total "memory item" procedure so I have typed it here from memory and it may not be worded exactly as in the QRH, but you get the general idea...

Interesting to note that this was one of the few instances when BA used the 380kts descent technique - it might be the only case actually.  It is up for debate whether the Olympus 593 would have been susceptible to ash or not considering the extremely high temperatures it ran at but I guess it could have played havoc with the intakes and shockwaves!

Frazz

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Craig Baillie

Interesting stuff also a lot of work has gone into creating risk categories so now there is an amount of ash that’s tolerable!

They’ve been telling us that Grimsvotn is days away from erupting since Feb; just more fun for 2020 :P.

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AdrianSmith

Surely highly unlikely that any volcanic ash would reach up to the levels used for "Supercruise", likely to stop just above tropopause?

Still an issue down at those levels of course.

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Fraser Gale
4 hours ago, AdrianSmith said:

Surely highly unlikely that any volcanic ash would reach up to the levels used for "Supercruise", likely to stop just above tropopause?

Still an issue down at those levels of course.

Not sure to be honest, but I guess a serious eruption could get to FL500 or so, but don't quote me as I don't know enough about it.  When the drill was written they probably weren't sure either which is why they'd try to account for all situations. 

I was trying to find my oldest flying manual to see if it was included in the early drills or if it was added after the BA Jumbo incident near Jakarta.  Interestingly BA were considering removing the 4 engine flameout drill from the book until the Jakarta incident happened..... 

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